1. Field of the Invention
The present invention relates to a system of optical line protection, and partially, relates to a device and a method of optical line protection in SDH/SONET (synchronous digital hierarchy/synchronous optical network).
2. Description of the Prior Art
In a system of optical line protection of SDH/SONET, previously, particularly as shown in FIG. 15, a management and control card 601 has mainly and intensively performed a control of each physical interface card and a processing of K1-K2 control information.
The K1-K2 control information is embedded in an overhead of an SDH/SONET signal in advance, and by extracting and inserting that information, the control of switching of the optical lines from the current system to the spare system is performed. In FIG. 15, the circuit for terminating the physical layer on a current system physical interface card 201W of the own station side device extracts the K1-K2 control information from the overhead, and transfers it through S501 to the management and control card 601. On the contrary, from the management and control card 601, the K1-K2 control information is inserted into the circuit for terminating the frame of SDH/SONET and the overhead on the current system physical interface card 201W through S502. The transfer of the K1-K2 control information on the spare system physical interface card 201P is also similar, and the exchange of information is performed by using signal lines S503, S504. On the optical line signal reception side, the frame of SDH/SONET and the overhead information are terminated in all physical interface cards in the device, and only the K1-K2 control information is taken out through a separately arranged signal line, and is sent to the management and control card (601), and similarly, on the signal transmission side, only the K1-K2 control information is sent from the management and control card (601) through a separately arranged signal line to the physical interface card, and is put on the overhead on the frame of SDH/SONET. That is, the management and control card (601) performs termination processing of the K1-K2 control information from all physical panels, and further, by performing the tri-state control (for example, control by S505, S506, S2505, S2506) of the gate for passing a signal (301) going toward a switch block (401), it controls the switching from the current system to the spare system or from the spare system to the current system of a signal from each physical interface card.
Here, in the case where a plurality of optical line ports exist on the physical interface card, or in the case where the device has a configuration of a plurality of physical interface cards in which a plurality of optical line ports are packaged, it is necessary to provide a signal line for the K1-K2 control information processing separately for each optical line port. Furthermore, it is also necessary to similarly separately provide a signal line for the tri-state control for opening and closing of the gate of a signal line leading toward the switch block 401. Thus, it is necessary to have dedicated hardware and software for performing optical line protection on the management and control card, and further, as the number of optical ports to be switched increases, the number of signal lines to be provided also increases, and the process for performing the switching also becomes more complicated, and as a result, the execution time for the switching itself is increased, which is a defect.
It is a main object of the present invention to provide an optical line protection device and a method, in which the configuration of the device is not complicated but simple and the switching of the optical lines can be performed at a high speed, even when a plurality of physical interface cards are packaged and a plurality of optical ports also exist on the card, and even when the switching commands of the optical line or the like are produced by turns because of the degradation such as a trouble or an error of the optical transmission line, or the manual operation from the superior management system, in the case of a configuration having a lot of optical ports because of the hugeness of the device.
Furthermore, it is an object to provide an optical line protection system, in which the configuration of the device is efficient and simple and the switching of the optical lines can be performed at a high speed, even in such a configuration where there is no frame signal for inserting K1-K2 control information and other overhead signals in order to increase the band of use, and continuous packet data is directly converted into light and is inputted or outputted as a line signal.
The optical line protection according to the present invention comprises protection means for performing optical line protection by using K1-K2 information inserted into a payload of a packet, for each physical interface.
Furthermore, the optical line protection system according to the present invention is the above described optical line protection system, in which the above described protection means includes: a filter for separating a payload of user data and a payload including K1-K2 information according to a control signal in a received payload; a selector for switching user data to be transmitted or K1-K2 information to be transmitted after adding a control signal of a value corresponding thereto; and control means for controlling an output buffer to a switch block and creating K1-K2 information to be transmitted and communicating with a physical interface card of another system on the basis of K1-K2 information in a payload including K1-K2 information outputted from the above described filter.
Furthermore, the optical line protection system according to the present invention is the above described optical line protection system further including means for detecting a trouble of the physical port by performing a CRC check on the basis of a payload length and a CRC code thereon.
The optical line protection in SDH/SONET according to the present invention includes protection means for performing optical line protection by using K1-K2 information inserted into an overhead of an SDH/SONET frame, for each physical interface.
Furthermore, the optical line protection in SDH/SONET according to the present invention is the above described optical line protection system in SDH/SONET, in which the above described protection means includes: extracting means for extracting the above described K1-K2 information from a received overhead; inserting means for inserting K1-K2 information to be transmitted into an overhead to be transmitted; and control means for controlling an output buffer to a switch block and creating K1-K2 information to be transmitted and communicating with a physical interface card of another system on the basis of K1-K2 information outputted from the extracting means.
Furthermore, the optical line protection in SDH/SONET according to the present invention is the above described optical line protection system in SDH/SONET further includes means for detecting a trouble of the physical port by performing a CRC check on the basis of a payload length and a CRC code thereon.